Inter-process communication

For other uses, see IPC.

In computing, Inter-process communication (IPC) is a set of methods for the exchange of data among multiple threads in one or more processes. Processes may be running on one or more computers connected by a network. IPC methods are divided into methods for message passing, synchronization, shared memory, and remote procedure calls (RPC). The method of IPC used may vary based on the bandwidth and latency of communication between the threads, and the type of data being communicated.

There are several reasons for providing an environment that allows process cooperation:

• Information sharing
• Speedup
• Modularity
• Convenience
• Privilege separation

IPC may also be referred to as inter-thread communication and inter-application communication.

The combination of IPC with the address space concept is the foundation for address space independence/isolation.^[1]

Main IPC methods

Method	Provided by (operating systems or other environments)
File	Most operating systems
Signal	Most operating systems; some systems, such as Windows, implement signals in only the C run-time library and provide no support for their use as an IPC method
Socket	Most operating systems
Message queue	Most operating systems
Pipe	All POSIX systems, Windows
Named pipe	All POSIX systems, Windows
Semaphore	All POSIX systems, Windows
Shared memory	All POSIX systems, Windows
Message passing (shared nothing)	Used in MPI paradigm, Java RMI, CORBA, MSMQ, MailSlots, others
Memory-mapped file	All POSIX systems, Windows; this method may carry race condition risk if a temporary file is used

Implementations

There are several APIs which may be used for IPC. A number of platform independent APIs include the following:

• Anonymous pipes and named pipes
• Common Object Request Broker Architecture (CORBA)
• Freedesktop.org's D-Bus
• Distributed Computing Environment (DCE)
• Message Bus (Mbus) (specified in RFC 3259)
• MCAPI Multicore Communications API
• Lightweight Communications and Marshalling (LCM)
• ONC RPC
• Unix domain sockets
• XML XML-RPC or SOAP
• JSON JSON-RPC
• Thrift
• TIPC
• ZeroC's Internet Communications Engine (ICE)

The following are platform or programming language specific APIs:

• Apple Computer's Apple events (previously known as Interapplication Communications (IAC)).
• Enea's LINX for Linux (open source) and various DSP and general purpose processors under OSE
• IPC implementation from CMU.
• Java's Remote Method Invocation (RMI)
• KDE's Desktop Communications Protocol (DCOP)
• Libt2n for C++ under Linux only, handles complex objects and exceptions
• The Mach kernel's Mach Ports
• Microsoft's ActiveX, Component Object Model (COM), Microsoft Transaction Server (COM+), Distributed Component Object Model (DCOM), Dynamic Data Exchange (DDE), Object Linking and Embedding (OLE), anonymous pipes, named pipes, Local Procedure Call, MailSlots, Message loop, MSRPC, .NET Remoting, and Windows Communication Foundation (WCF)
• Novell's SPX
• PHP's sessions
• POSIX mmap, message queues, semaphores, and Shared memory
• RISC OS's messages
• Solaris Doors
• System V's message queues, semaphores, and shared memory
• Distributed Ruby
• DIPC Distributed Inter-Process Communication
• OpenBinder Open binder
• IPC Shared Memory Messaging from Solace Systems

See also

• Computer network programming
• Communicating Sequential Processes (CSP paradigm)
• .NET Remoting
• Microkernel
• Nanokernel
• Protected procedure call

References

1. ^ Jochen Liedtke. On µ-Kernel Construction, Proc. 15th ACM Symposium on Operating System Principles (SOSP), December 1995

• Stevens, Richard. UNIX Network Programming, Volume 2, Second Edition: Interprocess Communications. Prentice Hall, 1999. ISBN 0-13-081081-9
• U. Ramachandran, M. Solomon, M. Vernon Hardware support for interprocess communication Proceedings of the 14th annual international symposium on Computer architecture. Pittsburgh, Pennsylvania, United States. Pages: 178 - 188. Year of Publication: 1987 ISBN 0-8186-0776-9

• Crovella, M. Bianchini, R. LeBlanc, T. Markatos, E. Wisniewski, R. Using communication-to-computation ratio in parallel program designand performance prediction 1-4 December 1992. pp. 238-245 ISBN 0-8186-3200-3

External links

• Linux ipc(5) man page describing System V IPC
• Windows IPC
• Beej's Guide to Unix IPC
• Unix Network Programming (Vol 2: Interprocess Communications) by W. Richard Stevens